Smoking article

ABSTRACT

A smoking article comprising a first part comprising a first ventilation area rotatable relative to a second part comprising a second ventilation area to control a level of ventilation by an overlap between the first and second ventilation areas. The first ventilation area and/or second ventilation area is configured such that the overlap has an increasing rate of change with respect to a rotational position. The second ventilation area overlaps with the first ventilation area from a first longitudinal position on the first part to a second longitudinal position on the first part. The first and second ventilation areas are configured such that the first and second longitudinal positions of the overlap increases in longitudinal distance along the smoking article from a mouth end as the level of ventilation increases.

TECHNICAL FIELD

Embodiments of the invention relate to a smoking article, a filter assembly for a smoking article, a component for smoking articles and a method of manufacturing a smoking article.

BACKGROUND

EP 0,228,211 describes a filter device for a smoking rod, in which a plurality of apertures are formed on a wrapper. The wrapper is rotatable such that the apertures are rotatable into and out of alignment with an air permeable part of the filter, formed by a notch. The ventilating apertures extend uniformly in a circumferential row. The present disclosure improves on the state of the art, as set forth herein.

SUMMARY

The present invention provides, in a first aspect, a smoking article comprising: a first part comprising a first ventilation area rotatable relative to a second part comprising a second ventilation area to control a level of ventilation through the first and second ventilation areas, wherein the second ventilation area overlaps with the first ventilation area over an overlap area extending from a first longitudinal position on the first part to a second longitudinal position on the first part, and the first and second ventilation areas are configured such that the first and second longitudinal positions of the overlap area increase in longitudinal distance from a mouth end along the smoking article as the level of ventilation increases.

The present invention provides, in a second aspect, a filter assembly for a smoking article comprising: a first part comprising a first ventilation area rotatable relative to a second part comprising a second ventilation area to control a level of ventilation through the first and second ventilation areas, wherein the second ventilation area overlaps with the first ventilation area over an overlap area extending from a first longitudinal position on the first part to a second longitudinal position on the first part, and the first and second ventilation areas are configured such that the first and second longitudinal positions of the overlap area increase in longitudinal distance along the smoking article from a mouth end as the level of ventilation increases.

The present invention provides, in a third aspect, a component for a smoking article comprising: a first part comprising a first ventilation area rotatable relative to a second part comprising a second ventilation area to control a level of ventilation through the first and second ventilation areas, wherein the second ventilation area overlaps with the first ventilation area over an overlap area extending from a first longitudinal position on the first part to a second longitudinal position on the first part, and the first and second ventilation areas are configured such that the first and second longitudinal positions of the overlap area increase in longitudinal distance along the smoking article from a mouth end as the level of ventilation increases.

The present invention provides, in a fourth aspect, a method of manufacturing a smoking article comprising: forming a first part having a first ventilation area; forming a second part having a second ventilation area; attaching the first and second parts such that the first part and second part control a level of ventilation through the first and second ventilation areas, wherein the second ventilation area overlaps with the first ventilation area over an overlap area extending from a first longitudinal position on the first part to a second longitudinal position on the first part; and the first and second ventilation areas are configured such that the first and second longitudinal positions of the overlap area increase in longitudinal distance along the smoking article from a mouth end as the level of ventilation increases.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention(s) will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

FIG. 1 is a graph illustrating the relationship between ventilation level and angle of rotation for a related art smoking article;

FIG. 2 is a perspective view of part of an exemplary smoking article according to some embodiments in a partially formed state;

FIG. 3 is a schematic plan view of a further embodiment of ventilation apertures according to the present invention;

FIG. 4 is a graph illustrating an exemplary relationship between ventilation level and angle of rotation for an exemplary smoking article according to some embodiments of the present invention, and

FIG. 5 is a graph illustrating exemplary relationship between smoking article pressure drop and level of ventilation for an exemplary smoking article according to some embodiments of the present invention and for a related art smoking article.

DETAILED DESCRIPTION

FIG. 1 shows an analysis of a ventilation level 100 of a smoking article determined in the development of the present invention. The smoking article has a row of uniform ventilation apertures, which may be selectively aligned with a larger ventilation aperture by rotation. An uncovered ventilation aperture, i.e. coinciding with the further ventilation aperture, allows ventilation air into the smoking article. The graph illustrates that at zero degrees of rotation, zero ventilation apertures are uncovered. The number of ventilation apertures uncovered, proportional to the area of ventilation apertures uncovered, is proportional to the angle of rotation. The ventilation level 100 is seen to increase as a part is rotated, and the number of ventilation apertures aligned with the larger ventilation aperture increases.

However, the relationship between the rotation of a part of the smoking article and level of ventilation is not proportional. In particular, it has been determined that the relationship between ventilating area and level of ventilation is not proportional. When relatively few ventilation apertures are uncovered, uncovering a further ventilation aperture has a relatively large effect on the ventilation level. When relatively many ventilation apertures are already uncovered, uncovering a further ventilation aperture has a relatively small effect on the ventilation level. The angle of rotation required to increase the ventilation level by a particular amount varies over the range of rotation.

The ventilating area is defined herein as the coincident (or overlapping) areas between the ventilation areas of components that are relatively displaceable, which allows ventilating air to pass into the smoking article, and in particular, into the filter.

The level of ventilation may be based on the amount of ventilating air which is permitted to enter the smoking article, and in particular the filter, during use.

The ventilating air may be considered as the air entering the filter through controllable ventilation areas only, or alternatively, may be considered as the air entering through the controllable ventilation areas and a base level of ventilation, for example, from any fixed ventilation areas and/or through an exterior covering of the filter (i.e. paper wrapping having a permeability). The level of ventilation is generally expressed as a percentage, based on the ventilating air entering the filter as a proportion of the total air drawn from the filter.

The level of ventilation shown in FIG. 1 is based on the air entering the filter through controllable ventilation areas only, as a proportion of the total air drawn from the filter. The x-axis scale of angle of rotation may be replaced by a linear measure of the number of equally sized ventilation apertures which are uncovered, which is proportional to the angle of rotation.

FIG. 2 shows an example of a smoking article according to an embodiment of the present invention. The smoking article may be an article such as a cigarette, cigar or cigarillo, whether based on tobacco, tobacco derivatives, expanded tobacco, reconstituted tobacco or tobacco substitutes and also heat-not-burn products (i.e. products in which flavour is generated from a smoking material by the application of heat without causing combustion of the material). For convenience, these will be referred to as “smoking articles” in this specification.

FIG. 2 shows a smoking article 1 in a partially formed state. The smoking article 1 comprises a first part having a source of smokable material 11, for example, tobacco. The source of smokable material 11 is in the form of a tobacco rod. The smoking article 1 further comprises a filter assembly 10 attached to the source of smokable material 11. The smoking article comprises a movable part, movable to select a ventilation level. In this example, the movement is a rotation. In some embodiments, the smoking article may optionally comprise a limiting mechanism, configured to limit movement to a pre-determined range.

The filter assembly 10 comprises a first filter section 12 and a second filter section 14. The first filter section 12 is attached to the source of smokable material to form a single unit. The tobacco rod and first filter section 12 are connected with a covering layer to affix the first filter section 12 to the tobacco rod, for example formed of tipping paper. The tobacco rod and first filter section are referred to as a first part of the smoking article, or as a tobacco unit. The elongate tobacco rod and first filter section define a longitudinal axis of the smoking article.

A second part of the smoking article comprises the second filter section 14. The second filter section 14 is co-axial with the first filter section 12, and is located rearwardly of the first filter section 12.

The second part of the smoking article further comprises a sleeve 13 in the form of a cylindrical tube extending around the circumference of the tobacco rod ii and/or first filter section 12. The material of the sleeve 13 is substantially impermeable to air, and can be formed as a tube, e.g. a cylinder. The sleeve can be made from a blank of sheet material. The sheet material can be paper. The tobacco rod and first filter section are dimensioned to rotate as a unit around a longitudinal axis within the sleeve 13. The second filter section 14 is at a mouth end of the sleeve 13, adjacent to the first filter section 12. The second filter section 14 is securely attached and fixed within the sleeve.

The first and/or second filter sections are made of a conventional filtration material, e.g. cellulose acetate tow. The filtration material is wrapped in a sheet material, for example paper, e.g. plugwrap.

Exemplary embodiments of smoking articles are provided with a ventilation system configured to allow adjustment of a ventilation of the smoking article. The ventilation system comprises one or more ventilation areas, comprising and/or defining ventilation apertures or air permeable material, in one or each of the first part and second part. For example, when ventilation areas in the sleeve and layers of sheet material around the first and/or second filter sections are aligned or overlap, air can flow into the body of the first and/or second filter section. The ventilation is selected by selecting a position of the second part relative to the first part. The position may be measured in degrees of rotation. The range of rotation can be limited to a predetermined range between a minimum and maximum ventilation, for example, 120 degrees.

The tobacco unit 11,12 comprises one or more first ventilation areas 32. In some aspects, the first ventilation area 32 is in the form of a plurality of discrete ventilation areas in a longitudinally and circumferentially extending area. The first ventilation area is elongate, in this example, in a longitudinal direction. The first ventilation area may extend circumferentially over only a part of the circumference. The first ventilation areas may extend around a single circumferential position. The first ventilation aperture 32 allows ingress of air into the tobacco unit, for example, into the first filter section 12. The first ventilation area 32 comprises one or more apertures or air permeable areas allowing air into the filtration material of the first filter section 12, through the layers of generally impermeable sheet material surrounding the filtration material.

In the example shown, the first ventilation area has a ventilating area which increases in area per unit length in a longitudinal direction. In particular, the circumferential extent of the ventilating area of the first ventilation aperture increases away from a mouth end of the smoking to provide for higher ventilation when an area further from the mouth end is selected by overlap with the second ventilation area. The ventilating area of the first ventilation aperture has a circumferential extent which increases uniformly, i.e. at a constant rate. Thus, in this example, the ventilating area of the first ventilation aperture increases at a constant rate, i.e. proportionally to the longitudinal position of the area of overlap.

The sleeve 13 may be provided with one or more second ventilation areas 30. The sleeve 13 may comprise a single second ventilation area 30 which is elongate. For example, the second ventilation area 30 is in the form of an elongate area. The elongate area can be a single aperture (as shown) or can comprise a plurality of ventilation apertures. The second ventilation area 30 can be a narrow slit. The second ventilation area extends at an angle to a circumferential direction, and at an angle to a longitudinal direction. The elongate second ventilation area extends in a combination of a longitudinal direction and a circumferential direction. In particular, the elongate second ventilation area 30 defines an axis, which extends lengthwise or longitudinally along the elongate aperture. The axis extends in a combination of the longitudinal direction and a circumferential direction of the smoking article. The axis can be considered as extending diagonally, relative to the longitudinal axis of the smoking article. The angled elongate second ventilation area 30 provides for a rotational only movement between the first and second parts of the smoking article to cause a longitudinal only movement of the overlap area along the first ventilation area.

In some examples, the second ventilation area has a substantially constant width along its length. The second ventilation area extends in a substantially straight line. Alternatively, the second ventilation area has a non-uniform width and/or extends in a curved line. In some aspects, the second ventilation area extends as an elongate diagonal area in a combination of a longitudinal and circumferential direction.

Ventilation through the first and second ventilation areas 30, 32 is dependent on alignment of the defined apertures which cooperate to form an overlapping opening area, which is determined by the rotational position of the first part of the smoking article relative to the second part of the smoking article. The second ventilation area 30 is movable rotationally relative to the first ventilation area 32, to control a ventilation level by an overlap between the ventilating areas of the first and second ventilation areas 30,32. The rotation between the first and second parts of the smoking article is configured to vary the position of an overlapping area of the first and second ventilation areas along an overlap path of the first and second ventilation areas. Thus the overlap path is a movement of the overlapping area of the first and second ventilation areas with relative movement between the first and second parts of the smoking article.

In this example, the overlap path is a longitudinal path. The relative rotation of the first and second ventilation areas provides a longitudinal movement of the overlap area of the first and second ventilation areas. The different longitudinal positions are controlled by rotation of the second part defining the second ventilation area relative to the first part defining the first ventilation area. The variation in ventilation is controlled by the degree of overlap between the ventilating areas of the first and second ventilation areas 30,32. In particular, a part only of the first ventilation area is aligned with a part only of the second ventilation area. The ventilation level is determined by the smaller of the ventilating area of the first or second ventilation areas in the overlapping region.

FIG. 3 shows an example of the first ventilation area 32 according to an embodiment of the invention, for use with the smoking article described with respect to FIG. 2. The first ventilation area 32 has a ventilating area which is not uniform along its length. The ventilating area of the first ventilation area 32 varies in area along a path over which the second ventilation area 30 moves.

The first ventilation area 32 comprises a plurality of discrete ventilating areas, termed ventilation elements 34. Each ventilation element 34 is a discrete aperture or permeable area. The configuration of the ventilation elements 34 provides for an overlapping area which varies along the overlap path. The ventilation elements 34 can have a pattern, sizing and/or spacing which varies such that a ventilating area of the first ventilation area increases in a first direction. The first direction corresponds with a direction of the overlap area in which the ventilation of the smoking article 1 increases away from a mouth end of the smoking article, i.e. the ventilating area of the first ventilation coinciding with the second ventilation area increases. The selectable ventilating area of the first ventilation area is determined by the sum of the ventilation elements per unit length and/or overlapping the second ventilation area. Alternatively, the first ventilation area can be a single aperture with edges shaped to provide the required level of ventilation.

The first ventilation area extends at a substantially constant circumferential position. The circumferential extent of the ventilating area of the first ventilation area varies along the longitudinal extent of the first ventilation area, as described above, to provide a ventilating area which varies along the overlap path. Any variation in circumferential position is not intended to affect the area of overlap or longitudinal position of overlap. In some examples, the ventilating area of the first ventilation area is substantially symmetrical around a longitudinal line at a constant circumferential position.

The first ventilation area increases in ventilating area by varying the number of first ventilation elements 34 in a direction perpendicular to the longitudinal path (i.e. circumferentially) on movement of a selected area along the first ventilation area (i.e. longitudinally). The selected area is selected by overlap with the second ventilation area. For example, the first ventilation elements 34 may be arranged in an array or other pattern. The number of rows in the array in a circumferential direction varies along the path of movement of the selected area. The number of rows can vary from one to the number of rows which fit within the second ventilation area 30. The rows can extend beyond the second ventilation area 30 in a direction perpendicular to the path of movement, but such rows may not contribute to ventilation.

The second ventilation area 30 is movable relative to the first ventilation area 32 along an overlap path from left to right, as shown. The rotation between the first and second parts is not shown, only the effect of rotation by moving the second ventilation area 30 longitudinally along the first ventilation area 32 is shown.

A first position 130 a of the second ventilation area 30 with respect to the first ventilation area 32 corresponds to a relatively low ventilation. The second ventilation area 30 is aligned with a plurality of first ventilation elements 34 having a relatively low ventilating area. The first ventilation elements 34 overlapping with the second ventilation area 30 in the first position 130 a are arranged in a single row.

In a second position 130 b, the second ventilation area 30 is aligned with a greater ventilating area of first ventilation area, by virtue of alignment with a greater number of rows of first ventilation elements 34. As the second part rotates, the or different sections of the second ventilation area continuously rotate into overlap with different sections of the first ventilation area. The different sections of the first ventilation area are at different longitudinal positions, such that the area of overlap moves longitudinally.

In a third position 130 c, the second ventilation area 30 is aligned with a still greater ventilating area of first ventilation area, by virtue of alignment with a still greater number of rows of first ventilation elements 34. The smoking article has a substantially maximum ventilation when the second ventilation area 30 is in the third position 130 c. The rotation of the second part is continuous relative to the first part, such that the area of overlap moves continuously in a longitudinal direction along the first ventilation area.

The terms “first ventilation area” and “second ventilation area” are intended to refer to the overall outline of the first and second ventilation areas respectively.

The first and second ventilation areas comprise ventilating areas through which air can pass, and optionally further comprise one or more non-ventilating or impermeable areas through which ventilating air cannot pass. For a ventilation area which is only a single aperture (as shown for the second ventilation area), then the ventilation area and the ventilating area are the same. For a ventilation area comprising a plurality of discrete ventilation elements, the ventilating area comprises both a ventilating area and a non-ventilating area (impermeable area). The ventilation area can be defined as the area over which the ventilating areas extend, i.e. as defined by the extreme or outlying ventilating areas. The term “overlap area” is used to describe an overlap of ventilation areas, including both ventilating areas and non-ventilation areas. Alternatively, the overlap area can refer to the whole area of the smaller of the first and second ventilation areas (e.g. second ventilation area).

The term “ventilating area” is used to refer to an effective area through which ventilation can occur, in particular an area which is both air permeable and aligned with a ventilating area of the other of the first or second ventilation area. The ventilating area can be considered as an effective ventilating area selected by the other of the first or second ventilation area. The first and/or second ventilation area can be considered as selecting or selected areas.

The second ventilation area 30 shown in each position 130 a,130 b,130 c in FIG. 3 is only part of the second ventilation area 30. It will be appreciated that the second ventilation area 30 extends further than shown in each position 130 a,130 b,130 c, such that on rotation of the second part of the smoking article a further part of the second ventilation area 30 is brought into circumferential alignment with the first ventilation area 32. This further part of the second ventilation area 30 is at a different longitudinal position, e.g. position 130 a,130 b,130 c, due to the angle of the elongate second ventilation area 30.

As illustrated in FIG. 3, a same length of the second ventilation area 30 is aligned with a portion of the first ventilation area (ventilating and non-ventilating areas) from positions 130 a to 130 c. This is different to the second ventilation area overlapping with an increasing area of the first ventilation area, as the first ventilation area is moved relative to the second ventilation area. For example, the present invention differs from an embodiment in which the second ventilation area overlaps from zero area of the first ventilation area to a maximum area determined by the area of the first and/or second ventilation area. In some aspects, shown in the embodiment of FIG. 3, the ventilating area is determined by the extent of the ventilating area of the first ventilation area in a direction perpendicular to the direction of movement of the overlap with the second ventilation area. For example, the circumferential extent determines the ventilating area. Alternatively, the overlap area can be determined by the extent of overlap in a same direction as the overlap path of movement.

The first ventilation elements 34 may have a circular outline, as in the example shown. Alternatively, the first ventilation elements 34 have any shape, for example, square, triangular, elliptical or rectangular. One or more dimensions of each first ventilation element 34 may consecutively increase. For example, a dimension parallel to the path of movement may increase and/or a dimension perpendicular to the path of the movement may increase. For the circular first ventilation elements 34 shown, the diameter increases, i.e. a dimension parallel to the path of movement increases and a dimension perpendicular to the path of the movement increases. The shapes of the first ventilation elements 34 do not need to have axes parallel or perpendicular to the path of the movement. The ventilating area of each first ventilation elements 34 determines the level of ventilation. Alternatively, the first ventilation aperture is a single aperture having a shape arranged to obtain the required overlap area with the positioning of the second ventilation aperture.

The spacing of the first ventilation elements 34 can be substantially uniform. For example, the centre of the first ventilation elements 34 is substantially constant, although as the dimensions of the first ventilation elements 34 increase, the extent of impermeable material between the first ventilation elements 34 decreases or stays constant. Alternatively, the spacing between centres of the first ventilation elements may increase or decrease. The extent of impermeable material between the first ventilation elements 34 stays constant, decrease or increase, in any combination.

The first ventilation elements 34 are configured to each have substantially the same area. The spacing of each first ventilation element 34 is also substantially constant. The change in ventilation area is provided in some embodiments only by the extent that the first ventilation area is perpendicular to the path of relative movement of the overlap with the second ventilation area. Alternatively, the first ventilation elements 34 may each have an area and/or spacing which varies. The variation in spacing allows the first ventilation area to comprise an increasing number of first ventilation elements in the first direction per unit length. In some implementations, the spacing of the first ventilation elements decreases in the first direction.

The second ventilation area is configured to rotate relative to the first ventilation area to select an overlap area. The longitudinal position of the overlap area varies according to the rotational positional of the first part of the second part. In some aspects, the second ventilation area overlaps with the first ventilation area from a first longitudinal position on the first part to a second longitudinal position on the first part. The first and second longitudinal positions define the longitudinal extremes of the overlap and/or overlapping ventilating areas. The first and second ventilation areas are configured such that the first and second longitudinal positions of the overlap increases in longitudinal distance along the smoking article from a mouth end as the level of ventilation increases. The overlap area refers to the whole area of the first and second ventilation areas, outlined by ventilating areas, which coincide.

The first and second longitudinal positions can alternatively or additionally be considered as the longitudinal positions which the effective ventilating areas of the first and second ventilation areas extend between. Thus, the first and second ventilation areas are configured such that the first and second longitudinal positions of the ventilating areas of the overlap increases in longitudinal distance along the smoking article from a mouth end as the level of ventilation increases.

The longitudinal extent of the overlap area, i.e. the distance between the first and second longitudinal positions, can be substantially constant during movements between the first and second parts of the smoking article. Variation in the first longitudinal position is substantially the same as variation in the second longitudinal position, with relative movement of the first and second parts of the smoking article.

Thus, the whole area of overlap of the ventilation areas travels longitudinally (away from the mouth end) as the level of ventilation is increased. The overlap is determined by the longitudinal edges of the first ventilation area. The overlap or overlap does not necessarily relate to the area through which ventilating air can enter the smoking article. In particular, both longitudinal extremes of the area of overlap are movable longitudinally, which is different to only one extreme of the area of overlap moving longitudinally. In particular, movement of the whole overlap area (i.e. both longitudinal extremes) provides for a greater variation in effective distance from the mouth end than movement of only one longitudinal extreme. This has an advantage that the open cigarette pressure drop can be made more constant.

The second ventilation area overlaps with the first ventilation area over a substantially constant longitudinal extent of the first part. In some examples, the longitudinal extent is not exactly constant due to the geometry of the circumferentially tapering first ventilation area and the diagonal second ventilation area. In particular, the longitudinal extent of the overlap area will increase towards higher levels of ventilation. This increase is separate from the overall movement of the overlap area away from the mouth end of the smoking article at higher ventilations. The overlap area can be considered as the smaller of the first and second ventilation areas, and in particular, the second ventilation area. The overlap area is therefore a constant size, and a constant longitudinal extent between the first and second longitudinal positions. The longitudinal extent is the longitudinal extent defined by the smaller of the first and second ventilation areas, i.e. the longitudinal extent of the second ventilation area.

The ventilating area within the overlap area of the first and second ventilation areas has an increasing rate of change with respect to a position of the first ventilation area 32 relative to a second ventilation area 30. The ventilating area increases on relative movement in a first direction between the first and second ventilation areas towards a higher ventilation of the smoking article, and in addition, the rate of change of the ventilating area increases with position in the first direction. The first direction corresponds with a direction in which the ventilation of the smoking article 1 increases, i.e. the overlap with the ventilating area of the second ventilation area increases.

In some aspects, the ventilation area of the first ventilation area 32 per unit length along the overlap path increases in a first direction of movement. The first ventilation area 32 is configured such that an increasing ventilating area per unit length of the second ventilation area moves into overlap with the second ventilation area. Thus, the ventilating area provided by an overlap between the first and second ventilation areas increases in the first direction. Thus, the increase in ventilating area is not linear (i.e. not directly proportional) to the respective displacement of the first and second parts. Instead, the overlap or ventilating area can increase in a non-linear manner. In particular, the effective ventilating area increases as a function which increases more quickly with position than a function which is linear (proportional) (i.e. a fixed relationship or first order relationship) to the position of the first and second parts. In other words, the overlap or ventilating area is higher than a linear relationship with relative displacement of the first part and second part. In some embodiments, the function of the ventilation area with position results in a level of ventilation of the filter, or smoking article, which is substantially linear (proportional) relative to the position of the first part relative to the second part. The position of the first part relative to the second part is along the path of movement, in the first direction. In an alternative embodiment, the increase in ventilation area can be substantially linear with respect to the relative displacement of the first and second parts.

The configuration of the first and second ventilation areas provides for selection of distinct and longitudinally spaced areas of overlap. The overlap areas are continuously selectable, such that the overlap can be at any point. This selection of different areas of the first ventilation area allows for a high change in longitudinal distance of the overlap area from the mouth end. Thus, the longitudinal length of filtration section downstream of the overlap area can be significantly varied. This improves the ability of the smoking article to maintain a substantially constant pressure drop. In particular, the pressure drop is relatively constant even when the level of ventilation varies significantly.

In particular, the angled orientation of the elongate second ventilation area provides for selection of a particular longitudinal position of the first ventilation area, by applying a selected rotation. The selected area of the first ventilation area determines the area of overlap, and hence the level of ventilation. The selected area of the first ventilation area also determines a pressure drop of the smoking article.

The movement of the overlap area forwardly along the smoking article, i.e. increasing distance from the mouth end, corresponds with increasing ventilation. Thus, the pressure drop of the smoking article is relatively constant. In particular, the pressure drop is more constant than if the longitudinal position of the smoking article were substantially constant.

In FIG. 3, the increase in rate of change of the ventilating area from positions 130 a to 130 c is derived from the increase in proportion of ventilating area (compared to a non-ventilating area) of the first ventilation area, which is present within an area corresponding to the second ventilation area. For example, the ventilation can be considered as determined by the ventilating area of the first part within a selected area. In accordance with some embodiments of the present invention, the first ventilation area may define a ventilating area per unit length which increases with relative displacement of the ventilation areas. The increase in the effective ventilating area is thus not constant with respect to the relative displacement, and has an increasing rate of change (i.e. an increasing increase) with respect to relative displacement, such as the angle of rotation. The increasing rate of change of the overlap area is provided by the shape of the area of the first ventilation area (and/or second ventilation area). In particular, the extent of the first ventilation area perpendicular (i.e. circumferentially) to the overlap path (i.e. longitudinally) varies in a non-linear relationship with the angle of rotation required to obtain that overlap position. In particular, the ventilating area of the selected part of the first ventilation area has a higher area than a directly proportional relationship with position of the selected area and/or the position of the first part relative to the second part. Thus, movement of the first part of the smoking article relative to the second part simultaneously causes the position of the effective ventilating area to move away from the mouth end of the smoking article, and the size of the ventilating area to increase.

FIG. 4 shows an illustrative example of an expected ventilation level 400 of a smoking article according to some embodiments of the present invention, which is varied by rotation. The graph illustrates that at zero degrees of rotation, zero controllable ventilation apertures are uncovered. As the angle of rotation increases, the number of ventilation apertures uncovered increases, and the area of uncovered ventilation apertures increases. This relationship between angle of rotation and number or uncovered area of ventilation apertures is not linear, as described above. The filter is configured such that the ventilation level 400 increases substantially linearly, and in particular proportionally, to the angle of rotation of the first part relative to the second part. The angle of rotation required to increase the ventilation level through the controllable ventilation areas by a particular amount is substantially constant over the range of rotation. That is to say, the relationship is linear or substantially linear. Thus, discrete relative movements of the first part with respect to the second results in the same change in level of ventilation for each movement, independently of the actual level of ventilation, i.e. whether the level of ventilation is relatively low or high. This contrasts with the art shown in FIG. 1, where a particular movement at a high ventilation would be expected to have a relatively small effect on the level of ventilation.

The level of ventilation shown in FIG. 4 is based on the air entering the filter through controllable ventilation areas only, as a proportion of the total air drawn from the filter. The effect of ventilating air entering through fixed size ventilation areas and/or through permeable wrapping of the filter, which may provide a base level of ventilation, is not illustrated. Including the base level of ventilation would provide a relationship having a non-zero, base, level of ventilation at zero angle of rotation. The level of ventilation, including the base ventilation air, may have a substantially linear relationship with the angle of rotation between the first and second parts. A linear equation may be written in which the level of ventilation is substantially equal to a product of a first constant (or slope) and angle of rotation, plus the base level of ventilation (second constant).

In FIG. 4, the x-axis scale of angle of rotation may be replaced by the number of equally sized ventilation apertures, or the ventilation area which is uncovered. These quantities would not be uniformly spaced along the x-axis, but each unit would be increasingly closely spaced in order to correspond with a linearly rising level of ventilation.

The definition of a zero degree of rotation providing zero uncovered ventilation areas is arbitrary. The smoking article or filter may be defined such that at zero degrees of rotation, a pre-defined ventilation area is uncovered. This does not affect the linear relationship between the angle of rotation and the level of ventilation.

FIG. 5 shows an example of a predicted change in pressure drop of the smoking article as the level of ventilation is increased, for a smoking article where the ventilating air enters at a fixed distance from the mouth end by line 501. In particular, as the level of ventilation increases, the open cigarette pressure drop decreases. It is desirable to have a cigarette pressure drop which is as constant as possible as the ventilation varies.

FIG. 5 also illustrates an exemplary open cigarette pressure drop by line 502 for a smoking article where the ventilating air enters at an increasing distance from the mouth end (DME) as the level of ventilation is increased. The pressure drop is substantially constant. The relationship shows some variation in pressure drop, but this is significantly reduced compared to the pressure drop for a smoking article where the ventilating air enters at a fixed distance from the mouth end (DME). In particular, the substantially constant, or more constant, pressure drop (PD) is due to the variation in longitudinal position of the ventilation overlap area as the ventilation is increased as described above. This can be considered as increasing the contribution to the pressure drop of the filter downstream of the open ventilation apertures.

The data on which the graph is based is shown in Table 1 below:

PD due to filter Distance from mouth PD from down- PD from filter up- Ventilation PD from Open smoking PD with DME at tobacco end end of ventilation stream of stream ventilation Area tobacco article PD with constant at (30 mm section) (mm) ventilation (Closed) (%) rod variable DME 20 mm 100 25.00 83.33 16.67 80 40 94.67 81.34 100 20.00 66.67 33.33 60 40 96.00 96.00 100 11.00 36.67 63.33 40 40 98.67 110.67 100 1.00 3.33 96.67 20 40 112.67 125.33

Alternatively, the level of ventilation may be substantially linear when including the ventilating air entering through the controllable (variable) ventilation areas only. Including the base ventilation air in the level of ventilation results in a non-linear relationship between the level of ventilation and the angle of rotation. The level of ventilation is still closer to a linear relationship with the displacement between the first and second parts than is conventionally known.

The present examples provide for a ventilating area which substantially increases per unit length along the path of relative movement. The increase is not required to be a continuous increase, in which any movement results in an increase of ventilating area per unit length. For example, the spacing of discrete first ventilation elements with air impermeable areas means that movement to additionally align an impermeable area with the second ventilation area will not result in an increase in ventilation.

Alternatively, the increase in size of the first ventilation elements does not need to be in consecutive first ventilation elements. For example, two or more first ventilation elements may have the same dimensions, with further first ventilation elements having the different dimensions. Thus, the increase of ventilating area per unit length can be a general trend, for example, over substantially the whole range of movement of the first part. In some examples, the disclosed embodiments may include one or more regions within the range of movement in which the ventilating area does not increase per unit length, and still provides an increase of ventilating area per unit length over substantially the whole range of movement.

The ventilating area through which air can flow into the smoking article through the first and second ventilation areas has been described in some embodiments, for example, as being nonlinear, such that there exists an increasing rate of change with respect to a position of the first ventilation area relative to a second ventilation area. Thus, the overlapping ventilating areas are greater than a proportional increase (i.e. fixed ratio, or constant slope term) in overlap area with respect to position along the path, and the amount of the increase in area will be larger towards higher ventilations. This relationship between ventilating area and position may apply to the whole range of relative movement between the first and second ventilation areas, a substantial part of the range of relative movement, or only a part of the range of relative movement. In mathematical terms, a derivative of the ventilating area with respect to position along the path of movement is a function of the position along the path of movement and/or, a second derivative of the ventilating area with respect to position along the path of movement is non-zero, and in particular, is a positive amount.

In some aspects, the sleeve 13 comprises one or more further ventilation areas (not shown). The further ventilation area(s) may provide ventilation which is independent of the rotational position of the position of the first and second parts of the smoking article. The further ventilation area(s) provides a base level, or minimum, ventilation to the smoking article. The further ventilation area(s) allows air through the sleeve, and into the second filter section 14. The second filter section 14 comprises filtration material surrounded by a porous paper wrap (e.g. plugwrap), which allows the ventilating air into the filtration material of the second filter section 14. The further ventilation area comprises a plurality of apertures extending circumferentially in a line.

In some implementations, the sleeve 13 comprises a separation line (not shown), which extends substantially circumferentially. The sleeve is configured to easily break along the separation line 36 into a forward part and a rearward part. The rearward part is affixed to the second filter section 14. The forward part is affixed to the first filter section 12, for example, by adhesive. Optionally, the forward part of the sleeve 13 connects the tobacco rod ii and first filter section 12. The separation line 36 is defined by a plurality of perforations through the sheet material (e.g. paper) of the sleeve 13. In use, the forward and rearward parts of the sleeve are initially connected. The smoking article has a defined initial ventilation, set by the further ventilation area, and a pre-determined initial alignment of the first and second ventilation areas 30, 32. In some embodiments, the sleeve is not readily rotatable (or slidable) relative to the tobacco unit. In some implementations, application of a rotational force to the rearward part of the sleeve 13, relative to the tobacco unit, breaks the sleeve 13 along the separation line 36. The sleeve 13 is then rotatable to vary the ventilation by alignment of the first and second ventilation areas.

The ventilation areas in the sleeve and/or tobacco unit are formed as apertures, e.g. by a laser. For example, the laser simultaneously generates aligned ventilation apertures in the sleeve and tobacco unit. Alternatively, the ventilation apertures are formed as a slit by a mechanical cutting tool. Alternatively, the ventilation apertures are formed as a cut-out area. Alternatively, the ventilation areas are formed by an air permeable material, which is either manufactured as a permeable material or made permeable by the addition of apertures or by processing.

The smoking article optionally comprises a limiting mechanism configured to limit rotation between the first and second parts. The limiting mechanism is configured to limit rotation to a pre-determined range. In some aspects, the pre-determined range of rotation is through an angle of from 90 to 180 degrees, and may be, for example, 120 degrees. The limiting mechanism limits rotation between a position in which the first and second ventilation areas have no overlap, and a further position in which the first and second ventilation areas are in full overlap.

The position of the second part relative to the first part can be controlled by an indexing mechanism such as a ratchet, pawl and detent mechanism or indexer, configured to provide indexed rotation between a plurality of discrete positions. The control mechanism may optionally provide an audible sound indicating movement to or from the selected position. The indexing mechanism comprises a first indexing section (or surface) on the tobacco unit, for example, on the first filter section 12. The first indexing section can be engaged with a second indexing section (or surface) on the sleeve 13. The indexing mechanism provides a number of indexed positions, in some implementations at least three, preferably at least five or seven, within a limited range of rotation, e.g. 90 or 120 degrees.

In an exemplary indexing mechanism, the first indexing section has a plurality of depressions which are engageable by a protruding feature on the second indexing section. The depressions preferably form a corrugated exterior surface, comprising a plurality of elongate grooves, separated by ridges, which extend substantially longitudinally.

The second indexing section comprises one or more protrusions which are engageable with the first indexing section. The protrusion(s) comprise one or more pawls, formed by one or more layers of sheet material which are folded to extend radially inwardly from the sleeve 13. The term “pawl” is intended to mean any type of protrusion which can engage with an indexing section to allow indexed movement in two directions. The pawl is formed on a substrate, which may be a sheet material, for example, paper. The substrate is affixed to an interior surface of the sleeve 13. The substrate is folded to define the pawl as an upstanding ridge of sheet material, forming an edged peak. The pawl has a substantially triangular cross-section. The indexing mechanism is separate and distinct from the limiting mechanism configured to limit the range of rotation between the first and second parts.

The smoking article is configured to restrain the sleeve 13 from moving longitudinally over the tobacco unit. For example, the grooves, and optionally ridges, of the first indexing section has a radius which is less than forwardly and rearwardly adjacent parts of the first part. The second indexing section is configured to engage with the forwardly and rearwardly adjacent parts, such that the second indexing section is retained longitudinally within the first indexing section. The first indexing section has a longitudinal extent which is substantially the same as the second indexing section to prevent relative longitudinal movement between the first and second parts.

The first and/or second filter section comprises an adsorbent additive. In some examples, the adsorbent additive is carbon, for example, charcoal and in particular, activated carbon. Alternatively, the adsorbent additive is a resin. In some aspects, the adsorbent additive is distributed within the filtration material of the first filter section 12. The adsorbent additive is substantially uniformly distributed in the filtration material. The adsorbent additive can be granules of carbon.

The first ventilation elements of any embodiment can be in a single row, or can be in more than one row, or an irregular number of rows that may or may not be aligned with the path through which the first and second ventilation apertures align. The first ventilation elements can be in arranged in a straight line or regular array. Alternatively, the first ventilation elements can be in arranged in any arrangement which allows overlapping with the second ventilation area according to some embodiments. For example, the row of first ventilation elements is not be straight or aligned with the path of movement, and/or the array is be irregular. Alternatively, the first ventilation area of any embodiment varies by having an increasing number of ventilation elements perpendicularly to the path of movement.

The second ventilation area has been described as rotatable relative to a first ventilation area to control a ventilation level. Alternatively, the second ventilation area may be slidable longitudinally relative to a first ventilation area to control a ventilation level. The relative longitudinal movement of the first and second parts is parallel to the longitudinal axis of the smoking article. Rotational and longitudinal movement can similarly be combined to provide helical relative movement between the first and second parts. Any of the embodiments described are equally applicable to a longitudinal movement and position. In particular, the path of movement is longitudinal, with the first direction in a forward or rearward direction to increase the level of ventilation. The position can be measured as a linear length along the path of movement. The longitudinal movement of the two parts is a telescopic movement with the sleeve of the second part slidable around an exterior of the first part. The extendable smoking article comprises a limiter or other limiting means to limit extension and/or an indexing means to provide indexed positions.

The first ventilation area has been described as located on an inner, first part of the smoking article, and the second ventilation area as located on an outer, second part of the smoking article, which surrounds a part of the first part. Alternatively, the described configuration of the first ventilation area is used for the second ventilation area on the second part, and/or, the described configuration of the second ventilation area are used for the first ventilation area on the first part. The first or second ventilation areas are used as the inner or outer ventilation area, since the ventilating area is determined by the overlap between the first and second ventilation areas.

The first ventilation area has been described as having a ventilating area which increases per unit length, and the second ventilation area has been described as having a constant area per unit length. Alternatively, both the first ventilation area and second ventilation area may have a ventilating area which increases per unit length. The ventilating area increases per unit length in a first direction towards an increasing ventilation, for example, as the overall overlap increases of the regions around the first and second ventilation areas. The first direction for the first ventilation area is therefore in an opposite direction to the second ventilation area, e.g. opposite rotational sense, or opposite longitudinal direction.

The second ventilation area has been described as a single area or aperture. Alternatively, the second ventilation area comprises a plurality of discrete ventilation areas, termed ventilation elements. Each ventilation element is a discrete aperture. The configuration of the ventilation element provides for the ventilation level described above. The ventilation elements has a pattern, sizing and/or spacing which varies such that a ventilating area per unit length increases in the first direction. Alternatively, the ventilation elements defines a ventilating area which is substantially constant in the first direction. The ventilating area of the second ventilation area is determined by the sum of the ventilation elements per unit length or overlapping the first ventilation area.

The smoking article has been described as having components formed from layers of sheet material, e.g. paper, defining the ventilation areas. Alternatively, different materials can be used. For example, one or more components allowing movement between the first and second part may be made of a plastics material. Such component(s) also define the ventilation area(s), for example, as apertures.

The disclosure has been described as applied to a smoking article. Any of the features may also be applicable to a filter for a smoking article, a filter assembly for a smoking article or a component of a smoking article. In particular, the ventilation is provided into the filter, and so the filter and associated assembly providing the first and second parts may form the basis of the invention. Any of the features may also apply to a method of manufacturing a filter or a smoking article.

Any of the features of any embodiment may be combined with any of the features of any other embodiment.

Embodiments of the invention(s) are configured to comply with applicable laws and/or regulations, such as, by way of non-limiting example, regulations relating to yields, constituents, testing, and/or the like. For example, the invention may be configured such that a smoking article implementing the invention is compliant with applicable regulations before and after adjustment by a user. Such implementations may be configured to be compliant with applicable regulations in all user-selectable positions. In some embodiments, the configuration is such that a smoking article implementing the invention meets or exceeds required regulatory test(s) in all user-selectable positions, such as, by way of non-limiting example, the testing threshold(s)/ceiling(s) for cigarette yields and/or smoke constituents.

In order to address various issues and advance the art, the entirety of this disclosure shows by way of illustration various embodiments in which the claimed invention(s) may be practiced and provide for superior forming of an inner and outer layer of a smoking article. The advantages and features of the disclosure are of a representative sample of embodiments only, and are not exhaustive and/or exclusive. They are presented only to assist in understanding and teach the claimed features. It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects of the disclosure are not to be considered limitations on the disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the scope and/or spirit of the disclosure. Various embodiments may suitably comprise, consist of, or consist essentially of, various combinations of the disclosed elements, components, features, parts, steps, means, etc. In addition, the disclosure includes other inventions not presently claimed, but which may be claimed in future. 

1. A smoking article, comprising: a first part including a first ventilation area, and a second part including a second ventilation area, the first part rotatable relative to the second part to control a level of ventilation through the first ventilation area and the second ventilation area, wherein the second ventilation area overlaps with the first ventilation area over an overlap area extending from a first longitudinal position on the first part to a second longitudinal position on the first part, the first ventilation area and the second ventilation area configured such that the first longitudinal position and the second longitudinal position increase in longitudinal distance from a mouth end along the smoking article as the level of ventilation increases.
 2. The smoking article as claimed in claim 1, wherein the first ventilation area and/or the second ventilation area is configured such that a ventilating area of the first ventilation area and/or of the second ventilation area has an increasing rate of change with respect to a position of the first part relative to the second part.
 3. The smoking article as claimed in claim 1, wherein a ventilating area of the first ventilation area and/or of the second ventilation area varies non-linearly with respect to a position of the first part relative to the second part.
 4. The smoking article as claimed in claim 1, wherein the first part is rotatable relative to the second part, the smoking article configured such that relative rotation between the first part and the second part controls the first and second longitudinal positions of the overlap area.
 5. The smoking article as claimed in claim 1, wherein the first ventilation area and/or the second ventilation area has a ventilating area that increases per unit length along an overlap path in a first direction corresponding to an increasing level of ventilation.
 6. The smoking article as claimed in claim 1, wherein the first ventilation area and/or the second ventilation area is configured such that the level of ventilation of the smoking article is substantially proportional to a position along a path of the second ventilation area relative to the first ventilation area.
 7. The smoking article as claimed in claim 1, wherein the second ventilation area has a ventilating area that is elongate and has an axis that extends in a combination of a longitudinal direction and a circumferential direction.
 8. The smoking article as claimed in claim 1, wherein the first ventilation area has a ventilating area that varies in extent in a direction substantially perpendicular to a direction of movement of an overlap area between the first ventilation area and second ventilation area.
 9. The smoking article as claimed in claim 1, wherein the first ventilation area comprises a plurality of discrete first ventilation elements configured to provide ventilation.
 10. The smoking article as claimed in claim 9, wherein a quantity of the first ventilation elements, arranged perpendicularly to a direction of an overlap path, increases in a direction associated with an increasing level of ventilation.
 11. The smoking article as claimed in claim 9, wherein the first ventilation elements are arranged in an array having rows substantially aligned with an overlap path, wherein a number of the rows per unit length increases in a direction associated with an increasing level of ventilation.
 12. The smoking article as claimed in claim 1, wherein the first ventilation area is rotatable relative to the second ventilation area to control the level of ventilation.
 13. The smoking article as claimed in claim 1, wherein the smoking article further comprises: a limiting mechanism configured to limit relative movement between the first art and the second part to a pre-determined range.
 14. A filter assembly for a smoking article, comprising: a first part including a first ventilation area rotatable relative to a second part including a second ventilation area to control a level of ventilation through the first and second ventilation areas, wherein the second ventilation area overlaps with the first ventilation area over an overlap area extending from a first longitudinal position on the first part to a second longitudinal position on the first part, and the first ventilation area and the second ventilation area are configured such that the first longitudinal position and the second longitudinal position of the overlap area increase in longitudinal distance along the smoking article from a mouth end as the level of ventilation increases.
 15. A component for a smoking article, comprising: a first part including a first ventilation area rotatable relative to a second part including a second ventilation area to control a level of ventilation through the first and second ventilation areas, the second ventilation area and the first ventilation area configured to overlap over an overlap area extending from a first longitudinal position on the first part to a second longitudinal position on the first part, and the first ventilation area and the second ventilation area are configured such that the first longitudinal position and the second longitudinal position of the overlap area increase in longitudinal distance along the smoking article from a mouth end as the level of ventilation increases.
 16. A method of manufacturing a smoking article, comprising: forming a first part having a first ventilation area; forming a second part having a second ventilation area; and attaching the first and second parts such that the first part and second part control a level of ventilation through the first and second ventilation areas, wherein the second ventilation area overlaps with the first ventilation area over an overlap area extending from a first longitudinal position on the first part to a second longitudinal position on the first part, and the first ventilation area and the second ventilation area are configured such that the first longitudinal position and the second longitudinal position of the overlap area increase in longitudinal distance along the smoking article from a mouth end as the level of ventilation increases.
 17. The smoking article as claimed in claim 13, wherein the first and second ventilation areas are configured such that a ventilation level of the smoking article is substantially proportional to a position of the first and second parts in the pre-determined range. 